A prime process with client

primes.ex

# Run with
# $ iex primes.ex
# > Client.start

defmodule Primes do
  def is_prime(n) when n == 2 or n == 1 do
    true
  end

  def is_prime(n) when n > 2 do
    is_prime(n, n - 1)
  end

  def is_prime(_n, 1) do
    true
  end

  def is_prime(n, l) when rem(n, l) == 0 do
    false
  end

  def is_prime(n, l) do
    is_prime(n, l - 1)
  end

  def primes_till(n) do
    Enum.reduce(2..n, [], fn x, acc ->
      if is_prime(x) do
        [x | acc]
      else
        acc
      end
    end)
  end

  # def nth_prime(n) do
  #   
  # end
  def nth_prime(n, h \\ 1, p \\ 2) do
    if h <= n do
      if Primes.is_prime(p) do
        nth_prime(n, h + 1, p)
      end
    else
      nth_prime(n, h, p + 1)
    end
  end

  def find_factors(n) do
    cond do
      rem(n, n - 1) == 0 -> find_factors(n, n - 1, [n - 1])
      rem(n, n - 1) != 0 -> find_factors(n, n - 1)
    end
  end

  def find_factors(n, l) do
    if rem(n, l - 1) == 0 do
      find_factors(n, l - 1, [l - 1])
    else
      find_factors(n, l - 1)
    end
  end

  def find_factors(n, l, facs) do
    cond do
      l - 1 <= 1 -> facs
      rem(n, l - 1) == 0 -> find_factors(n, l - 1, [l - 1 | facs])
      true -> find_factors(n, l - 1, facs)
    end
  end
end

defmodule PrimeServer do
  def take_num() do
    IO.puts("Prime Server waiting for message")

    receive do
      {pid, :primes_till, n} -> send(pid, {:mes, Primes.primes_till(n), n})
      {pid, :is_prime, n} -> send(pid, {:mes, Primes.is_prime(n), n})
      {pid, :nth_prime, n} -> send(pid, {:mes, Primes.nth_prime(n), n})
      {pid, d} -> send(pid, {:error, "Found #{d}"})
    end

    take_num()
  end
end

defmodule Client do
  def start() do
    spawn(fn -> PrimeServer.take_num() end)
    |> Client.start()
  end

  def start(pid) do
    IO.puts("Select operation")
    IO.puts("1. primes till")
    IO.puts("2. if prime")
    IO.puts("3. nth prime")
    IO.write("> ")

    IO.read(:stdio, :line)
    |> String.trim()
    |> case do
      "1" ->
        IO.puts("primes till")

        IO.write("> ")

        IO.read(:stdio, :line)
        |> String.trim()
        |> String.to_integer()
        |> (&send(pid, {self(), :primes_till, &1})).()

        IO.puts("waiting")

        receive do
          {:mes, mes, n} ->
            IO.puts("primes till #{n}")
            IO.inspect(mes)
        after
          2_000 -> IO.puts("no message")
        end

      "2" ->
        IO.puts("is prime?")

        IO.write("> ")

        IO.read(:stdio, :line)
        |> String.trim()
        |> String.to_integer()
        |> (&send(pid, {self(), :is_prime, &1})).()

        receive do
          {:mes, mes, n} ->
            if mes do
              IO.puts("'#{n}' is a prime number")
            else
              IO.puts("'#{n}' is not a prime number")
            end

            IO.puts("")
        end

      "3" ->
        IO.puts("nth prime")
        IO.write("> ")

        IO.read(:stdio, :line)
        |> String.trim()
        |> String.to_integer()
        |> (&send(pid, {self(), :nth_prime, &1})).()

        IO.puts("waiting")

        receive do
          {:mes, mes, n} ->
            IO.puts("#{n}th prime is #{mes}")

          {:error, mes} ->
            IO.puts(mes)
        after
          2_000 -> IO.puts("no message")
        end

      x ->
        IO.puts("whaat")

        IO.inspect(x)
    end

    Client.start(pid)
  end
end